The Vilsmeier-Haack reaction has been an established method for the formylation of aromatic rings. Such formylation, however is applicable mainly to active substrates, such as amines and phenols, and aromatic hydrocarbons which are much more active than benzene such as azulenes and ferrocenes. Typically, POCl.sub.3 and dimethylformamide are used as the reactants, although other dialkyl formamides have been used as well. It is also widely used as a method for chlorinating, especially with thionyl chloride, under similar reaction conditions.
As disclosed in co-pending application Ser. No. 08/673,687, now U.S. Pat. No. 5,874,587, novel imidazolium cations are provided and methods for their preparation are described using intermediates containing N--C--C--N moieties which are reacted with N-substituted or N,N-disubstituted formamides in the presence of a halogenating agent. Methods are also disclosed therein for the preparation of compounds with two N--C--C--N moieties both reacted with the formamide reactant. Among other uses, the aforementioned compounds have remarkable color and/or fluorescent properties and have numerous industrial and pharmaceutical utilities.
In further studies of the chemistry, processes for facile synthesis, and utilities of the fluorescent compounds of the aforementioned application, the inventors herein have sought to both control and expand the selection of chemical moieties that may be provided as substituents on these and related compounds as well as provide compounds with one or more N--C--C--N groups which may be substituted as described. It is towards these objectives that the present invention is directed.